The present invention relates to lubricant concentrates and lubricant use compositions which include at least one sulfo methyl ester compound, and in particular to lubricant compositions which are employed as conveyor lubricants for use in the food and beverage industries, and to methods of using the same.
In most packaging operations, including beverage operations, containers are moved along mechanized conveyor systems in an upright position from station to station wherein various operations including filling, labeling, sealing, capping, and the like are performed on the containers. During some of the operations, the containers are open. In particular in the beverage industry, it is important that the containers move without hindrance along the conveyor such that no liquid is spilled onto the conveyor. This is particularly important for dairy based beverages such as milk because milk can coagulate on the equipment surfaces.
Such conveyor systems are thus typically lubricated to reduce friction between the package and the load bearing surface of the conveyor. Thus, these lubricants are typically applied to the conveyor belts to reduce friction between the package and the conveyor which facilitates unhindered conveyance of bottles on the conveyor belt. These lubricants, may also be referred to as chain conveyor or belt lubricants.
Not only are good lubricating properties important, there are other important considerations when selecting a lubricant for use in the beverage bottling industry. One such consideration is that the lubricant be compatible with the beverage such that it does not form coagulates or other solid deposits when it accidentally contacts spilled beverages on the conveyor system. The lubricant must also be readily cleaned from the equipment.
In the past, the lubricants commonly used on the load bearing surfaces of these conveyor systems typically contained fatty acid soaps as the active lubricating ingredient.
These fatty acid lubricants provided excellent lubricity, but are also known for forming insoluble precipitates in the presence of cations found in hard water such as calcium and magnesium. These precipitates can cause clogging of nozzles and subsequent loss of lubricant flow to conveyor surfaces. Water softening agents and chemical chelating or sequestering agents such as EDTA can be employed with these lubricants to prevent formation of such precipitates. However, strong chelating agents such as EDTA are also known for leaching calcium out of concrete which causes pitting in the concrete floor surfaces which are commonly found in beverage plants and dairy operations.
Amine-based lubricants are known and may be used as an alternative lubricant to the fatty acid based lubricants for lubricating conveyor systems. However, amine based lubricants tend to form precipitates with polyvalent anions such as carbonates and sulfates which are also present in hard water. This can lead to clouding of the lubricant solution. Furthermore, amine-based lubricants have been known to cause coagulation of milk which; is a disadvantage for use in dairy conveyor operations. The coagulation of milk results in soil build-up on equipment and environmental surfaces. This soil is aesthetically unappealing, difficult to clean and may, for a thorough cleaning, require dismantling of the equipment.
Soil build-up can also cause fouling of moving parts on container filling equipment. Such fouling can become a harbor for bacterial growth and subsequently lead to problems with product quality. More frequent cleaning and longer cleaning times may be required.
Preventing soil build-up resulting from milk coagulation can reduce the amount of time required for cleaning. Dairy operations and beverage plants are typically cleaned once a day providing that no problems arise from interaction between a lubricant solution contacting spilled products.
Consequently, there remains a need in the art for an improved lubricant that not only exhibits excellent lubricity, but which also functions well in hard water, is non-corrosive to soft steel and concrete, and which is compatible with and does not coagulate beverage products such as milk.
The present invention relates to lubricant concentrates and diluted lubricant use compositions which include an effective lubricating amount of at least one sulfo methyl ester.
Suitably, the sulfo methyl esters have the following general formula: 
where R=C10-C18 and more suitably about C12-C18. In some embodiments, the alkyl group is about C16 to about C18.
The sulfo methyl ester finds utility and exhibits lubricity at concentrations of about 0.1 to about 75 wt-%, suitably about 0.25 wt-% to about 50 wt-% and most suitably about 0.5 wt-% to about 10 wt-%.
For some applications, diluted use compositions may be in the range of about 0.1 wt-% to about 10 wt-%, and more suitably 0.25 wt-% to about 5 wt-%.
The sulfo methyl ester lubricants may be employed in combination with anti-corrosion agents such as ether diamines and/or dicarboxylic acids or salts thereof. Hard water, particularly well water, has been found to be highly corrosive to mild steel, for example.
Other adjuvants may also be optionally employed in the lubricant compositions according to the present invention. Such adjuvants include, but are not limited to, viscosity modifiers, soil anti-redeposition agents, preservatives, dyes, fragrances, anti-foaming agents, soil suspension and solubilizing agents, penetrants, antimicrobial agents, other surfactants, other hydrotropes, and so forth.
The lubricating compositions according to the present invention exhibit excellent lubricating properties, particularly in hard water conditions such as with well water, are noncorrosive, are non-pitting to both soft steel and concrete, and do not coagulate dairy products such as milk. This superior combination of properties makes the inventive lubricants highly desirable for use as lubricants in food and beverage operations.
The lubricating compositions according to the present invention are advantageously employed as conveyor lubricants in food and beverage operations. They have been found to be particularly useful as dairy conveyor lubricants because, unlike prior lubricants, they do not cause coagulation of milk.
The lubricating compositions according to the present invention are typically prepared as concentrates, and then diluted to an end use concentration prior to use.
The present invention further relates to methods of using the lubricant compositions according to the present invention. One such method includes lubricating a continuously-moving conveyor, system for transporting packages wherein the conveyor system is wetted with an aqueous lubricant composition including the sulfo methyl ester according to the present invention.
The lubricant composition may be provided to the end user as a concentrate, or the method may include the step of diluting the concentrate prior to application of the concentrate to the desirable location of the conveyor system. The lubricant composition may be applied to the conveyor system using a spray method. Application may involve applying the lubricant to the package itself.
These and other advantages of the present invention will be more readily understood by those skilled in the art from a reading of the following detailed description.
While this invention may be embodied in many different forms, there are described in detail herein specific embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.
The present invention relates generally to a lubricant concentrate, diluted use lubricant compositions and to methods of using the same.
A. The Sulfo Methyl Ester Lubricants
The lubricant compositions of the present invention include at least one sulfo methyl ester. Suitably, the sulfo methyl esters have the following general formula: 
where R=C10-C18.
In some embodiments according to the present invention, the alkyl group is about C16-C18. Such longer alkyl chains have been found to provide excellent lubricity.
Additionally, a certain amount of disodium 2-sulfo C12-C18 fatty acids are present. These fatty acids have the following general formula: 
Increase lubricity can be achieved with longer alkyl chains at lower concentrations. However, longer alkyl chains also tend to decrease the solubility of the sulfo methyl ester.
An example of a commercially available sulfo methyl ester is ALPHA-STEP@ MC-48 available from Stepan. The alkyl chain, R, has from 12 to 18 carbon atoms.
The concentrates are typically diluted with water in the range of about about 1 to about 1000, 1 to about 500 and more suitably about 1 to about 200.
The sulfo methyl ester concentrate finds utility and exhibits lubricity at concentrations of about 0.1 to about 75 wt-%, suitably about 0.25 wt-% to about 50 wt-% and most suitably about 0.5 wt-% to about 10 wt-%.
For some applications, diluted use compositions may be in the range of about 0.1 wt-% to about 10 wt-%, and more suitably 0.25 wt-% to about 5 wt-%.
B. Corrosion Inhibitors:
The sulfo methyl ester lubricants of the present invention may be advantageously used in combination with corrosion inhibitors. Examples of such corrosion inhibitors include, for example, ether amines, polycarboxylic acids such as carboxylic diacids, triacids, as well as the phosphate esters, or other salts, including sodium or potassium salts, thereof.
The present inventors have found that when at least one sulfo methyl ester lubricant is employed in combination with at least one ether amine and/or at least one polycarboxylic acid or salt thereof, and preferably both, the lubricant composition prevents corrosion of mild steel. For stainless steel, anti corrosion agents, in particular the dicarboxylic acid, provide no further benefits.
The ether amines suitable for use herein include linear and branched, and saturated and unsaturated alkyl ether amine compounds.
Suitable ether amines and diamines include those having the following general formulas: 
and mixtures thereof, wherein R1 may be linear C6-C18, R2 may be a linear or branched C1-C18 alkyl, and R3 is a linear or branched C1-C8 alkyl group. Ether diamines such as these are described in commonly assigned U.S. Pat. No. 5,723,418 and U.S. Pat. No. 5,932,526, and in U.S. Pat. No. 6,306,816, each of which is incorporated by reference herein in its entirety.
More specific examples of suitable ether diamine anti-corrosion agents are those having the following general formula:
ROC3H6NHC3H6NH2
where are R is a straight or branched chain alkyl group having from about 8 to about 30 carbon atoms. Examples of such ether diamines include, but are not limited to, octyl/decyloxypropyl-1,3-diaminopropane; isodecyloxypropyl-1,3-diaminopropane; isododecyloxypropyl-1,3-diaminopropane available from Tomah Products, Inc. under the tradename DA-16; dodecyl/tetradecyloxypropyl-1,3-diaminopropane; isotridecyloxypropyl-1,3-diaminopropane available from Tomah Products, Inc. under the tradename DA-17; tetradecyloxypropyl-1,3-diaminopropane available from Tomah Products, Inc. under the tradename of DA-18; and so forth; to mention only a few.
Another specific example of a commercially available ether amine is TOMAH(copyright) DA1618 which is a mixture of 60% N-dodecyloxypropyl-1,3-diaminopropane and N-tetradecyloxypropyl-1,3-diaminopropane available from Tomah Products, Inc. and having the following general formula:
ROCH2CH2CH2NHCH2CH2CH2NH2
where R is an alkyl group having 12 and 14 carbon atoms.
Suitable examples of polycarboxylic acids or salts thereof are those having the following general formula:
HOOCxe2x80x94Rxe2x80x94COOH
where R is an alkyl group having from about 1 to about 8 carbon atoms and more suitably about 1 to about 4 carbon atoms.
In some embodiments, the corrosion inhibitors are polycarboxylic acids such as dicarboxylic acids. Examples of useful dicarboxylic acids include, but are not limited to, adipic acid, glutaric acid, succinic acid or mixtures thereof. In one embodiment, a mixture of adipic acid, glutaric acid and succinic acid
The corrosion inhibitors are useful at concentrations of about 0.05% to about 25% and more suitably about 0.1% to about 20% in the concentrate. In one embodiment, the concentration of the corrosion inhibitor is about 0.5 wt-% to about 3 wt-%.
One example of a useful corrosion inhibitor is SOKALON(copyright) DCS diacid mixture available from BASF, Inc.
In one embodiment, an ether diamine is employed in combination with a mixture of diacids.
C. High Pressure Additives
The sulfo methyl ,ester lubricants of the present invention may be advantageously used in combination with ether carboxylates. The present inventors have found that when at least one ether carboxylate is employed, the high pressure lubricity is enhanced. Examples of useful ether carboxylates are those having the following general formula:
Rxe2x80x94(OCH2CH2)nxe2x80x94OCH2COOxe2x80x94X
where X is an alkali metal, amine, ether diamine, ammonium salt or H (free acid), R=C12-C18 and more suitably R=C13-C16 and n is about 6 to about 18.
High pressure lubricity, such as that required for in-floor conveyors in dairy operations, has been found to be enhanced through the use of ether carboxylates. High pressure lubricity can be measured using a Falex testing instrument. The ether carboxylate is useful from about 0.1 wt-% to about 50 wt-% of the concentrate, more suitably about 0.25 wt-% to about 25 wt-% and most suitably about 0.5 wt-% to about 5 wt-%.
Specific examples of ether carboxylates useful herein include, but are not limited to, trideceth-7-carboxylic acid available from Clariant Corp. under the tradename of SANDOPAN(copyright) DTC acid; laureth-5-carboxylic acid available from Clariant Corp. under the tradename of SANDOPAN(copyright) LA-8-HC; trideceth-19-carboxylic acid available from Clariant Corp. under the tradename of SANDOPAN(copyright) JA-36; branched nonylphenol ethoxylate-9-carboxylic acid available from Clariant Corp. under the tradename of SANDOPAN(copyright) MA-18; sodium ceteth-13-carboxylate available from Clariant Corp. under the tradename of SANDOPAN(copyright) KST-A; sodium laureth-13-carboxylate having the following general formula
Rxe2x80x94(OCH2CH2)nxe2x80x94OCH2COOxe2x80x94X
where R is an alkyl group having 12 and 15 carbon atoms, n is 12 and X is sodium available from Clariant Corp. under the tradename of SANDOPAN(copyright) LS-24.
D. Surfactants
Other surfactants may be optionally employed in the lubricant concentrates and diluted-use compositions of the present invention. Such surfactants should be selected and employed in amounts such that the properties of the lubricant according to the present invention, such as the non-coagulation of milk, for example, are not negatively impacted. Such surfactants are known to those of ordinary skill in the art.
E. Hydrotropes
Other hydrotropes may be optionally employed in effective amounts in the lubricant concentrates and diluted-use compositions according to the present invention to provide viscosity control and cold temperature stability of the concentrate. Examples of optional hydrotropes include, but are not limited to, the alkali salts of aromatic sulfonates including sodium linear alkyl naphthalene sulfonate, potassium linear alkyl naphthalene sulfonate, sodium xylene sulfonate, potassium xylene sulfonate, potassium or sodium toluene sulfonate, potassium or sodium cumene sulfonate, and so forth; n-octenyl succinic anhydride (NOS); ammonium cumene sulfonate; alkyl polyglucoside; and so forth. The above list is intended for illustrative purposes only and is not exhaustive. Hydrotropes are known to those of skill in the art and there are numerous types available for use.
E. Antimicrobial Agents.
It may be desirable to improve antimicrobial efficacy by adding, in addition to the other ingredients, one or more antimicrobial agents. Generally, any solid or liquid chemical agent having microbiocidal efficacy may be used in the invention. Chemical compositions known to impart microbiocidal efficacy include iodophors, phenolics, quaternary ammonium compounds, and so forth.
More specific examples of antimicrobial agents include, but are not limited to, cationic surfactants such as alkyl and benzyl quaternary compounds like N-alkyl (C12-18) dimethylbenzyl ammonium chloride, N-alkyl (C14-18) dimethylbenzyl ammonium chloride, N-tetradecyldimethylbenzyl ammonium chloride monohydrate, dimethyl didecyl ammonium chloride, and N-alkyl (C12-14) dimethyl 1-naphthylmethyl ammonium chloride which are available commercially from manufacturers such as Stepan Chemical Company, and so forth. The above lists are not exhaustive and are intended for illustrative purposes only. One of ordinary skill in the art has knowledge of such antimicrobial agents.
When present, an antimicrobial agent must have a concentration effectively necessary for the required action to be provided. Generally, in the lubricant concentrate the concentration of antimicrobial agent may range from about 0.1 to 10 wt-%, preferably from about 1 to 8 wt-%, and most preferably from about 2 to 6 wt-%.
F. Other Adjuvants
The lubricant concentrate and, in turn, lubricant use-composition of the invention may also include one or more other adjuvants to modify the character or properties of the compositions. Examples of other commonly employed adjuvants include viscosity modifiers, soil anti-redeposition agents, preservatives, dyes, fragrances, anti-foaming agents, soil suspension and solubilizing agents, as well as penetrants, and so forth. One of ordinary skill in the art is well versed in the type of adjuvants employed in such lubricant compositions.
The lubricant use-compositions of the present invention may be formulated as concentrates, and then later diluted to the lubricant use-composition, the dilution depending on the application for which the lubricant use-composition is being employed. Generally, the lubricant concentrate may be diluted with water anywhere from about 1 to about 1,000 times, and more suitably about 1 to about 400, and even more suitably about 1 to about 200 times, to provide the lubricant use-dilution which is desirable.
The sulfo-methyl ester based lubricants of the present invention function excellently in hard water, and thus require no chelating or sequestering agents to prevent precipitates from forming in hard water environments. The sulfo methyl ester based lubricant according to the present invention has been found to provide water hardness compatibility for the lubricant solution with water containing as much as 20 grains of water hardness without any chelating or sequestering agents. This is beneficial because strong chelating agents such as EDTA, for example, have been found to remove calcium and other cations from concrete leading to pitting of the concrete. Thus, being free from strong chelating or sequestering: agents is also an added advantage.
Another advantage of using the sulfo methyl ester based lubricants according to the present invention is that they do not cause coagulation of dairy products, particularly milk.
The lubricant compositions according to the present invention may be employed as conveyor lubricants for conveyor systems which move product or packages along the conveyor system through a series of operations which are performed on each package. These lubricants are sometimes referred to in the industry as belt lubricants. The lubricant compositions of the present invention find particular utility in conveyor beverage and food operations, particularly bottling type operations, wherein packages or bottles are moved via a conveyor through a series of operations including filling, capping, and so forth. Such packages or bottles are typically open during some of the operations and are thus moved along the conveyor while open.
The lubricants may be provided to the end user as a concentrate which requires dilution according to a set of instructions to a diluted use composition, or the lubricants may be provided in an already diluted, ready-to-use form.
The lubricants may be applied to the desirable location using a variety of application methods. One typical method involves spraying the diluted use lubricant composition onto the conveyor system. This may involve a series of spray heads located along the conveyor system.
The lubricating compositions facilitate the unhindered movement of containers along the conveyor system. This is particularly important in beverage operations such as bottling operations, particularly for the dairy industry. Spilled beverages can result in having to shut down the operation for cleaning, thus, the unhindered movement of the bottles along the conveyor system is very important in these operations. Furthermore, it is important that the lubricant be compatible with the spilled beverage such that precipitation, coagulation and solid deposits do not form. The lubricants of the present invention find particular utility in dairy operations because they do not cause coagulation of milk when they come into contact with it.
The lubricant compositions of the present invention may also be applied to the packages which are to be moved along the conveyor, although this is typically a less desirable method.
The following non-limiting examples further illustrate embodiments of the present invention.